An increasingly idle Congress is causing atrophy in many of the nation’s most muscular political forces.

The 50 largest lobbying spenders, including big corporations like AT&T and trade groups like the National Association of Realtors, collectively spent about $168 million lobbying Congress between April and June — a $30 million decline from their first quarter efforts, a POLITICO analysis of new lobbying disclosures indicates.

In some cases, the quarter-to-quarter lobbying dips are measured in seven-figures: AT&T spent $7.05 million during the year’s first quarter and $3.49 million during the second, while ExxonMobil dropped from $4.17 million to $2.77 million.

For the same time periods, pharmaceutical companies Pfizer ($3.6 million to $2.3 million), Novartis ($2.75 million to $1.44 million) and Johnson & Johnson ($2.27 million to $1.2 million) are among those who also reported notable spending decreases.

An across-the-board dip is a “direct reflection of the lack of any meaningful action by Congress to address the major issues facing our economy,” said Tita Freeman of the Business Roundtable, an association of leading corporate chief executives.

And looming late-year battles such as federal budget sequestration apparently remain too distant to prompt major lobbying forces to double down on their traditional Capitol Hill influence efforts — at least at this juncture.

Among manufacturers, General Electric, with $4.86 million in spending during the second quarter, is well off its pace from either the year’s first quarter ($5.89 million) or the second quarter of 2011 ($6.77 million.) And during the second quarter of 2010, when congressional health care and financial reform remained headline news, GE spent $15.46 million.

Even high-flying Google backslid from its all-time quarterly high of $5.4 million between January and March, spending close to $4 million between April and June. But that’s still about twice Google’s lobbying output from the second quarter of 2011.

Of the top 50 lobbying spenders, according to data from the Center for Responsive Politics based on first quarter filings, only 11 reported increases from the first quarter of the year. These trend buckers include Koch Industries (2.3 million to $3.07 million), BP ($2.23 million to $2.56 million), Altria ($2.2 million to $2.8 million) and the National Education Association ($2.25 million to $2.48 million).

The U.S. Chamber of Commerce last quarter spent $22.5 million, compared to $26.4 million in the first quarter, although that’s still a big increase over the second quarter of last year at $14.8 million. The pro-business Chamber, unlike most corporations and organizations, voluntarily includes state-level and grassroots lobbying efforts in its federal reports.

Overall spending by top 50 lobbying entities during this year’s second quarter is actually up several million dollars from the same period in 2011, although that’s solely attributable to the Chamber’s nearly $8 million increase in spending — by far, the most in the nation. Excluding the Chamber, second-quarter 2011 to second-quarter 2012 spending among top lobbying forces is nearly flat: about $145 million to $146 million.

Among notable companies not ranking among the nation’s biggest lobbying spenders, Facebook posted it’s largest quarterly number ever — $960,000 — easily exceeding its spending from the year’s first quarter ($650,000) or the same time last year ($320,000).

The social network company’s lobbying expansion is among the most notable in the nation: Consider that during the second quarter of 2010, it spent just $60,000, according to federal records.

For the largest defense contractors such as Boeing and Lockheed Martin, which could lose more than most if the federal government implements drastic budget cuts, their second quarter expenditures declined only modestly or remained flat.